A chemical equation is balanced when the number of each kind of atom is the same on both sides of the reaction.
Explanation:
The law of conservation of matter (except in nuclear reactions) indicates that atoms can neither be created or destroyed.
The number of atoms that are in the reactants must be the same as the number of the atoms that are in the product.
The number and types of molecules can (and will) change. The atoms that make up the molecules are rearranged but the number and kinds of atoms stay the same.
